using System;
namespace ConsoleApp3
{
    class Work3
    {
        static void Main(string[] args)
        {
            string a = "   ";
            string a1 = "null";
            string a2 = "";
            string a3 = null;
            Console.WriteLine(StringUtil.IsNull(a));
            Console.WriteLine(StringUtil.IsNull(a1));
            Console.WriteLine(StringUtil.IsNull(a2));
            Console.WriteLine(StringUtil.IsNull(a3));
            Console.WriteLine("********************");
            int[] arr = { };
            int[] arr1 = null;
            int[] arr2 = new int[2];
            int[][] arr3 = new int[3][];
            Console.WriteLine(ArrayUtil.IsNull(arr));
            Console.WriteLine(ArrayUtil.IsNull(arr1));
            Console.WriteLine(ArrayUtil.IsNull(arr2));
            Console.WriteLine(ArrayUtil.IsNull(arr3));
        }
        static class StringUtil
        {
            public static bool IsNull(string String)
            {
                if (String == null) { return true; }
                else { return false; }
            }
        }

        static class ArrayUtil
        {
            public static bool IsNull(Array arr)
            {

                if (arr == null) { return true; }
                else { return false; }
            }
        }
    }
}